The invention relates to medicine and biology, in particular to instruments for microscopic analyses and diagnoses, more precisely to devices for placing histological and biological samples in an optical medium for subsequent microscopic analysis.
Prepared and dyed histological and biological samples are accommodated (placed) in special media in order to create an optically uniform medium and preserve them for the time required for analysis. Various substances are used as the optical media, for example Canada balsam, Cedax or polystyrene. A drop (several drops) of a solution of one of the indicated substances in a suitable solvent is (are) applied to a sample located on the slide, and covered with a cover glass. After the solvent has dried, the samples placed in the optical medium can be preserved unchanged for several years.
Major laboratories specializing in histological and biological analyses in which hundreds of sections (samples) are processed every day use the highly productive devices.
The Consul device for placing samples from the English company Shandon (Shandon Consul. A versatile automatic coverslipper. Shandon Life Sciences Intern. Ltd. brochure) includes a cover glass storage bin with a pusher for laying out the cover glasses, a slide holder, optical medium solution metering dispenser, and a rolling unit.
The slide holder consists of half-frames secured to a rod and capable of rotating in a plane perpendicular to the rod. The rolling unit in the Consul device is comprised of a stage and two rollers, which are situated under the cover glass in the initial position. The stage and rollers are able to move perpendicularly to the plane of the cover glass, and the rollers are also capable of being deflected in conjunction with spring-loaded rockers.
The slides are mounted on a vertically placed bar. A swiveling device is used to move the slide to the working area. The cover glass storage device is mounted on a stand, just as the technological solution metering system.
The Consul device operates as follows:
Moving along a guide, the cover glass pusher shifts the lower glass from the storage bin to the working area. The dose of optical medium solution is dropped onto the cover glass from above. The swiveling device turns the half-frame with the slide around the rod, and delivers the slide into the working area, so that it comes to lie above the cover glass, sample down. The rolling unit stage lifts up, bringing the cover glass close to the slide. The rolling unit pusher continues to lift the rollers until they contact the cover glass, after which the spring-loaded rockers start to deflect, and the rollers roll on the surface of the cover glass. In this way, the central portion of the cover glass is compressed by the stage, while the rollers roll over the lateral portions. After this, the rolling unit descends, moves away from the slides, and the swiveling device returns the half-frame with placed slide to the initial position.
The Consul device makes it possible to place up to 400 samples an hour; the high productivity enables its successful use in laboratories specializing in pathohistological analyses.
The shortcoming to the Consul device is the horizontal arrangement of the cover glass and slide at the moment of pressing, which makes it more difficult to expel air pockets that form in the optical medium.
A device for placing samples according to U.S. Pat. No. 4,428,793, IPC3 B65C 9/08, published on Jan. 31, 1984, includes a storage bin for cover glasses, a stage for arranging slides, and means for removing the cover glass from the storage bin, moving it to the stage where the slide is located, and lowering the cover glass onto the slide for placing the histological sample. This means consists of a holder, which accommodates a vacuum suction device and spring-loaded pusher, wherein the suction device is situated higher than the pusher. The device is vertically lowered into the storage bin for cover glasses in such a way that the suction device grips the cover glass; the pusher spring compresses in the process, and it ends up at the same level as the suction device. After the cover glass has been removed from the storage bin, the pusher spring is opened, releasing the edge of the cover glass. The means transfers the glass to the stage with slide at an angle to the horizontal created by the equally high position of the suction device and pusher. The means releases the cover glass with the lower end on the edge of the slide, which accommodates the drop or strip of medium to be placed. The pusher holds down the cover glass as the specified medium is lowered. The pusher spring is here compressed until the suction device and pusher are on the same horizontal, after which the vacuum suction device is removed from the cover glass. As a result, the cover glass is lowered onto the slide incrementally, at an angle, which facilitates the removal of air pockets from the medium.
One shortcoming to the known device is that the single cover glass, the thickness of which does not exceed 0.06-0.25 mm, is difficult to separate from the foot of the slides in the storage bunker, all the more so since the foot of the slides is compressed by the spring-loaded pusher during each separation using the specified device. In addition, gripping the cover glass with the spring-loaded pusher while placing it on the slide with the force necessary to compress the spring might result in damage to the histological sample.
A device for removing and placing cover glasses according to U.S. Pat. No. 5,989,386, IPC6 B32 B31/04, published on Nov. 23, 1999, includes a head with one end accommodating two vacuum suction devices on planes situated at an angle relative to each other. Situated between the suction devices is a spring-loaded plunger, which is controlled by a solenoid and able to move up and down. When retracted, the plunger is unable to contact the cover glass. The head also encompasses a spring-loaded lever situated at the other end of the head, behind the suction device and plunger. The device operates as follows. The head is lowered into the storage bin with cover glasses until such time as the plunger contacts the uppermost glass, after which the suction device grips the uppermost glass. Exposed to the action of the plunger spring and angular orientation of the suction devices, the gripped cover glass bends and separates from the foot of the glass. The head transfers the cover glass to the slide. The opposing end of the cover glass gripped by the suction device is lowered with a lever, so that the cover glass lowers onto the slide at an angle to the horizontal. The head moves down until such time as the end of the cover glass gripped by the suction device comes to lie on the slide. The lever is secured to the head so as to move clockwise and counterclockwise, and places the cover glass on the slide, after which the suction device is detached.
The device according to U.S. Pat. No. 5,989,386 is intended to remove “a large percentage of free cover glasses”, but practice has shown that vacuum suction devices are unable to separate one free glass at a time, and the cover glass has to be taken out of the bin with other implements, after which the glass can be gripped by means of the suction device. As in the device according to U.S. Pat. No. 4,428,793, using a spring-loaded plunger and lever in this device can end up damaging the histological sample.
A device for placing histological samples according to U.S. Pat. No. 6,474,386, IPC7 B65 H29/24, published on Nov. 5, 2002, makes it possible to cautiously remove air from the space between the cover glass and slide. This device encompasses a platform for the slide and means for gripping and placing the glass on the slide at an inclination. The means for gripping and placing the cover glass include a cylinder mounted on the vertical stand, which is equipped with a motor and able to move up and down on the stand. The cylinder also incorporates a arm equipped with a separate motor, which is able to move clockwise and counterclockwise. A vacuum suction device joined with a vacuum pump is secured at the free end of the arm. The arm can lift the vacuum suction device and lower it to a level at which the gripped cover glass comes to lie horizontally.
The device according to U.S. Pat. No. 6,474,386 operates as follows.
A slide with histological sample and applied spot of medium are arranged on the platform for placement purposes. The gripping means use the suction device to grip one end of the cover glass and situated it above the slide in such a way that the gripped end comes to lie above the free end. The cylinder is then shifted down to a level where the horizontal axis where the arm is secured is lower than the slide situated on the platform. In this position, the lower end of the cover glass touches the edge of the slide at an acute angle to the horizontal. The arm is turned counterclockwise by a motor, and the cove glass held by the suction device is smoothly placed on the slide, after which the suction device is detached. It is stated that the device makes it possible to place the histological sample without damage.
One shortcoming to this device is that the cover glass has to be gripped with a vacuum suction device. This structural design requires a vacuum pump and quite complicated control, making the device heavier and more costly to manufacture.
The device for placing histological and biological samples [WO 2004/077051, IPC7 G01N33/48, published on Sep. 10, 2004] includes a working area, cover glass bin with slot in the lower part of the bin, a cover glass pusher embodied in the form of a plate with a thickness less than the thickness of the cover glass, a unit for placing the cover glass, which can be reciprocally displaced above the working area, and a press connected to the drive for reciprocally displacing the cover glass placing unit. This device is designed like a comb; the working area (platform for holding the slide) is bordered from the placing means by way of a vertical stop with cuts, into which the teeth of the comb engage; the press is designed as a cylinder segment or spindle.
The device according to WO 2004/077051 operates as follows:
The cover glass with histological sample onto which the spot (strip) of medium is to be applied is accommodated in the working area for purposes of placement. The comb (placement means) is located above the slide, and the pusher moves the cover glass over it from the bin. The cover glass descends at an angle to the slide, incrementally moving the comb from the space between the cover glass and slide. As the comb moves, the press is actuated, pressing the cover glass against the slide.
The device according to WO 2004/077051 makes it possible to place histological samples without air pockets and damage to sample tissue, and does not require pneumatic and vacuum devices that hamper control. However, it is associated with the following shortcomings.
Access to the working area for cleaning and other servicing operations is impeded by the fact that the comb and press with transmission system are located above it. In order to service the working area, the entire assembly needs to be dismantled. In addition, since the cover glasses of different manufacturers differ somewhat in width, the vertical stop with cuts does not provide for the accurate arrangement of the cover glass on the slide. The glass “wanders”, which makes it harder to continue working with the placed samples.